Wifi connection issue

Hi, I have a Gopigo3 robot with DexterOS. I decided to change OS because I had to use the tweeter function. To do this, I had to install Raspbian OS and I configured the network card to connect to the wifi of my phone. Everything works perfectly but when I decide to reuse Dexer OS contained on another SD card, the robot no longer emits wifi and a green LED flashes indefinitely.
I absolutely need to be able to connect with Dexter’s old OS without reinstalling it on the SD card because I need to recover programs from it.
Thank you in advance for your answer.

I unfortunately don’t know how to fix the issue, but I do know that you can recover the files. Do you have a Mac or Linux computer? If so then you can put the ad card in and recover the files easily.

the green LED that flashes is next to the power button?
If so, that means that specific SD card is somehow corrupted, and the Pi can’t boot up with it.

The problem may be elsewhere, so try to power the Raspberry Pi directly through the small USB connecter that’s on the Pi, just below the GoPiGo power button. There’s a small chance it may work.